The push for ever increasing device densities is particularly strong in complementary metal oxide semiconductor (CMOS) technologies such as in the design and fabrication of field effect transistors (FETs). FETs are the basic electrical devices of today's integrated circuits and are used in almost all types of integrated circuit design (e.g., microprocessors, memory, etc.). FETs may be formed on conventional substrates.
The advent of finFETs, i.e., field effect transistors formed on semiconductor fins having a height greater than the width, has altered the processing steps of conventional planar field effect transistors significantly. For example, semiconductor fins are formed by patterning a top semiconductor layer of a semiconductor-on-insulator (SOI) substrate. Thus, the conventional planar capacitor that employs an upper portion of a semiconductor substrate as a lower plate cannot be formed on a substrate including finFETs.
Resistors are devices that have electrical resistance associated with the device. Resistors are typically employed in an electrical device for protection, operation and/or current control. Hence, resistors play an important part in current analog and digital circuit designs. Using a fin-based technology would require a redesign of current CMOS resistor schemes for buried resistors (BRs), overpass resistors (Ops) and silicide resistors.